The invention relates to a joint fitting intended for use in a vehicle seat with a forward tiltable seat back which is provided with a first fitting part, a second fitting part and a pivot joint by way of which said two fitting parts are pivotally joined together.
In automotive vehicles with only two side doors in particular, the front seats usually have a forward tiltable seat back in order to facilitate access to the rear seats. Prior art joint fittings of the type mentioned herein above are described in DE 28 29 701 A, U.S. Pat. Nos. 4,269,446, 6,030,042 for example and have a hook hinged to the one fitting part, with said hook cooperating with a bolt provided at the other joint portion. After the hook is detached from the bolt, the fitting parts may be pivoted relative to each other about the hinge axle. As a result thereof, the seat back may be tipped forward. On tilting it back again, the movement is limited by a mechanical stop located between the first and the second joint fitting. Once this stop is reached, the corresponding angular position is secured between the two fitting parts by hooking said hook up onto the bolt.
Additionally, this type of vehicle seats also has a fitting that permits to adjust the inclination of the seat back relative to the seat carrier. The adjustment of this fitting requires quite a lot of time, though. The joint fitting of the type mentioned herein above permits to achieve a quick adjustment by a greater angle, e.g., 90xc2x0.
The previously known joint fitting is clearance-free because the hook contacts the bolt alongside a hook surface which, as the hook is increasingly pivoted about the bolt, increasingly pulls the bolt toward the pivot axis of the hook.
Normally, the hook is in its locking position. The hook is allocated an elastic means that biases said hook in the locking position. There is provided a traction means that acts on the hook and allows the hook to pivot out of its locking position against the action of the elastic means. The traction means ends in a handle which usually is located in the upper region of the seat back, on the side thereof. By actuating the handle, the hook is pivotally released for a quick adjustment of the seat back.
Said previously known joint fitting has proved its worth. In the known embodiments of the joint fitting, the paths on which the support is carried out are quite long. Accordingly, the lever arms are relatively large.
This is where the invention comes to bear. It is an object of the invention to indicate another construction of a joint fitting, in which the paths for support are short in the locked condition, which is of a compact design and in which the pivot bearing of the part responsible for the locking needs not be used to assist in providing compensation for play.
The solution to this object is embodied by a joint fitting intended to be used in a vehicle seat with forward tiltable seat back which is provided with a first fitting part, a second fitting part and a pivot joint by way of which these two fitting parts are pivotally joined together, said joint fitting being further provided with:
a locking cam pivotally hinged to the first fitting part about a cam axle and having a first end region located in proximity to the cam axle and a second end region located opposite to the first end region,
a locking bight configured on the second fitting part and provided with a first locking side and with a second locking side facing the first looking side, the distance between said locking sides matching the distance between the two end regions, and
an actuation device acting on the locking cam at a distance from the cam axle for moving the locking cam from a locking position in which the joint fitting is blocked into a release position,
wherein in the locking position the first end region of the locking cam buts on the first locking side and the second end region of the locking cam abuts on the first locking side and the second end region of the locking cam abuts on the second locking side and a circle having the pivot joint for center and passing through the cam axle intersects the first locking side, the second locking side being inside said circle.
In this joint fitting, the locking cam forms the stop needed to limit the return movement when the forward tipped seat back is reclined backward. Accordingly, a separate stop as it is provided with the prior art joint fitting is not necessary.
On the other side, in the locking position, the locking cam positions itself with its two end regions lying between the two locking sides of the locking bight. The locking cam, whose function is similar to that of the hook in the joint fitting of the art, not only provides fixation in one pivotal direction, but in the two possible pivotal directions of the seat back. As a result thereof, the pivot axis, i.e., the cam axle, is virtually not loaded, no clamping forces being at any rate introduced into the other fitting part via the cam axle, as this is the case with the prior art fitting. The first locking side may be located in immediate proximity to the cam axle so that the bearing of the locking cam may be simple. The clamping forces are generated by the end regions of the locking cam directly contacting the associated locking sides. In this locking position, the cam axle is no longer needed. It is needed to transmit the force and to move the locking cam into the release position and from there back into the locking position, but not for the locking process itself.
A clearance-free joint fitting is achievable by simple means. As compared to the prior art joint fitting, less parts are needed. Locking is performed with greater accuracy. As a result thereof, the transmission of the joint position of the joint fitting of one seat side to the joint fitting of the other seat side is facilitated and more accurate.
In a prior art joint fitting, the hook is the pivotal locking means. In the locking condition, the hinge axle of said locking means is pulled toward the locking region. With the joint fitting in accordance with the invention, the process is exactly reversed. In the locking condition, the free end of the locking cam pushes the pivot joint away. Since however, a support in the form of the end region located there, i.e., of the first end region, and of the first locking side is located in immediate proximity to the pivot joint, what determines the locking position is not the hinge axle but the fit of the locking cam and of the locking bight.
A circle having the pivot joint for center and passing through the cam axle also intersects the first locking side but remains outside of the second locking side. As a result thereof, the locking cam remains outside of the circular movement described by the second locking side and, more generally, by the locking bight when the seat back is tipped forward. On tilting it back, the first end region abuts on the first locking side, thus forming the described stop for the return movement.
Like in prior art, an actuation device is provided. But now, said actuation device acts onto the locking cam. Normally, the locking cam is in the locking position. By actuating the actuation device, it is pivoted from the locking position into the release position. As a result thereof, it is possible to quickly tilt the seat back forward.
In a preferred development, a torsion bar is arranged on the locking cam, said torsion bar elastically biasing said locking cam in one direction of rotation, which is opposed to the direction of rotation on tilting the seat back forward. As a result thereof, said torsion spring always loads the locking cam relative to the first fitting portion in the locking position and maintains it.
In a preferred development, on tilting the forward tipped seat back backward, the first contact occurs between the first locking region and the first locking side in one point of the first end region which is positioned in such a way relative to the cam axle that a pivoting moment is applied. Accordingly, the first contact causes the second end region to be moved toward the second locking side.
In a further improvement, it is suggested that the first locking side is oriented on a portion of a straight line that passes through the hinge axle. This permits to achieve precise abutment when the seat back is tilted back.
In an advantageous development, the actuation device has a control part which is hinged to the second fitting part. There is provided a traction means which is more specifically configured as a Bowden cable and allows the control part to pivot from its position of rest into a release position. The control part has a release arm that pushes the control cam from the locking position into the release position as the traction means is actuated. The locking cam is actuated in this manner. Although it is possible, in principle, to actuate the locking cam directly, the actuation via the control part has the advantage that the traction means can act on a part that moves together with the same fitting part as the handle of the traction means. Accordingly, it is not necessary to arrange the traction means in such a manner that no pull is exerted onto the traction means when the seat back is pivoted.
In another development, the control part has a retaining lug which engages behind a blocking side of the locking cam in the position of rest of the control part. In this way, the locking cam is mechanically blocked. It cannot be pushed out of the locking position, not even by acceleration forces acting onto the locking cam.